Polylactic acid resins have a high melting point and can be melt-molded; therefore, they have been investigated for various applications as a biodegradable polymer having a superior practicality. However, polylactic acid resins have a problem in their weatherability and, for instance, there is a problem in that polylactic acid resins become markedly deteriorated when left under the sun.
Meanwhile, it is known that hindered amine compounds serve as an effective additive in stabilization of many organic substrates containing polymer against adverse effects of light and oxygen. For example, Patent Document 1 discloses to blend an ultraviolet absorbing agent or hindered amine compound into a polylactic acid resin.
In addition, disclosed in Patent Document 2 as a weakly basic hindered amine compound is a compound having an alkyloxyamine structure. Further, disclosed in Patent Document 3 as weakly basic hindered amine compounds having various skeletons are hindered amine compounds having carboxylic acid ester structure, amide structure, carbamate structure and acetal structure.
Patent Document 1: Japanese Unexamined Patent Application Publication No. H6-184417
Patent Document 2: Japanese Examined Patent Application Publication No. S49-40557
Patent Document 3: Japanese Unexamined Patent Application Publication No. H1-113368